System and method for three-dimensional video coding

ABSTRACT

Systems and methods are provided for receiving and encoding 3D video. The receiving method comprises: accepting a bitstream with a current video frame encoded with two interlaced fields, in a MPEG2, MPEG4, or H.264 standard; decoding a current frame top field; decoding a current frame bottom field; and, presenting the decoded top and bottom fields as a 3D frame image. In some aspects, the method presents the decoded top and bottom fields as a stereo-view image. In other aspects, the method accepts 2D selection commands in response to a trigger such as receiving a supplemental enhancement information (SEI) message, an analysis of display capabilities, manual selection, or receiver system configuration. Then, only one of the current frame interlaced fields is decoded, and a 2D frame image is presented.

RELATED APPLICATIONS

This application claims the benefit of a provisional applicationentitled, SYSTEMS AND METHODS FOR STEREO VIDEO CODING, invented by Leiet al., Ser. No. 60,512,155, filed Oct. 16, 2003.

This application claims the benefit of a provisional applicationentitled, SYSTEMS AND METHODS FOR STEREO VIDEO CODING, invented by Leiet al., Ser. No. 60,519,482, filed Nov. 13, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to video compression and, moreparticularly, to a system and method of encoding/decoding compressedvideo for three-dimensional and stereo viewing.

2. Description of the Related Art

Conventional video compression techniques typically handlethree-dimensional (3D), or stereo-view video, in units of a frame. Themost straightforward method is to code two views separately, asindependent video sequences. This straightforward method, however,suffers from poor coding efficiency. It also has higher complexitybecause it needs to encode/decoder, multiplex/demultiplex, andsynchronize two bitstreams. To reduce the complexity of bitstreamhandling, synchronized frames from each view can also be groupedtogether to form a composite frame, and then coded into one singlebitstream. This composite-frame method still suffers from poor codingefficiency. It also loses a view-scalable functionality, i.e., decodercan choose to decode and display only one view.

Alternately, as noted in U.S. patent application 20020009137, one viewcan be coded into a base layer bitstream, and the other view into anenhancement layer. This layer approach not only has a better codingefficiency, but it also preserves the view-scalable functionality.However, this method still has higher complexity due to its needs tohandle multiple bitstreams (base-layer and enhanced-layer bitstreams).

It would be advantageous if compressed 3D video could be communicatedwith greater efficiency.

It would be advantageous if only one view of a compressed 3D orstereo-view could be decoded to permit viewing on legacy 2D displays.

SUMMARY OF THE INVENTION

The present invention treats 3D video frames as interlaced materials.Therefore, a 3D view can be coded using existing interlace-codingmethods, such as those in H.264, which enable better compression.Further, the invention supports a scalable coding (two-dimensional view)feature with minimal restrictions on the encoder side. The scalabledecoding option can be signaled in a simple SEI message, for example.

Accordingly, a method is provided for receiving 3D video. The methodcomprises: accepting a bitstream with a current video frame encoded withtwo interlaced fields, in a Motion Pictures Expert Group-2 (MPEG2),MPEG4, or ITU-T H.264 standard; decoding a current frame top field;decoding a current frame bottom field; and, presenting the decoded topand bottom fields as a 3D frame image. In some aspects, the methodpresents the decoded top and bottom fields as a stereo-view image.

In some aspects, the method accepts 2D selection commands in response toa trigger such as receiving a supplemental enhancement information (SEI)message. Other triggers include an analysis of display capabilities,manual selection, or receiver system configuration. Then, only one ofthe current frame interlaced fields is decoded, and a 2D frame image ispresented.

In one aspect of the method, a first encoded video frame is acceptedprior to accepting the current frame. Then, the method: derives apredictive first frame top field; and, derives a predictive first framebottom field. Then, the current frame top and bottom fields are decodedin response to the predictive first frame top field and predictive firstframe bottom field, respectively.

Likewise, a method is providing for encoding 3D video, comprising:accepting a current 3D video image, including a first view of the imageand a second, 3D, view of the image; encoding the first view as a frametop field; encoding the second view as the frame bottom field; and,transmitting a bitstream with a current video frame, having the topfield interlaced with the bottom field, into a channel.

Additional details of the above-described methods, and 3D video encoderand receiver systems are provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of the present invention 3D videoreceiver system.

FIG. 2 is a schematic block diagram of the present invention 3D videoencoding system.

FIG. 3 illustrates the present invention 3D view field interlacingprocess.

FIG. 4 is a graph illustrating a comparison of coding performance.

FIG. 5 is a flowchart illustrating the present invention method forreceiving 3D video.

FIG. 6 is a flowchart illustrating the present invention method forencoding 3D video.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic block diagram of the present invention 3D videoreceiver system. The system 100 comprises a decoder 102 having an inputconnected to a channel on line 104 to accept a bitstream with a currentvideo frame encoded with two interlaced fields. For example, line 104may be connected to the Internet, a satellite receiver, or a digitalcable network. The decoder 102 accepts the bitstream in a standard suchas MPEG2, MPEG4, or ITU-T H.264. The decoder 102 has an output on line106 to supply a decoded current frame top field and current frame bottomfield. A display 108 has an input to accept the decoded fields on line106. The display 108 visually presents the decoded top and bottom fieldsas a 3D frame image. For example, the display 108 can be ahigh-definition TV. In other aspects of the system, the display 108visually presents the decoded top and bottom fields as a stereo-viewimage.

Generally, the display 108 may visually presents a two-dimensional (2D)image in response to using only one of the decoded current frameinterlaced fields. Also, as a selected alternative to the presentationof the 3D image, the display 108 may present a 2D image in response tousing only one of the decoded current frame interlaced fields. Forexample, a user may manually select to view a 2D image, even if a 3Dimage is available.

In other aspects, the decoder 102 may analyze the display capabilitiesand decode only one of the current frame interlaced fields, if non-3Ddisplay capabilities are detected. For example, the decoder may detectthat display 108 is a legacy television. In this circumstance, thedisplay 108 visually presents a two-dimensional (2D) image.

In some aspects, the decoder 102 receives a supplemental enhancementinformation (SEI) 3D content message with the current video frame. Thereare many types of conventional SEI messages. The 3D content SEI messageis a message acts as a signal that the referenced frame(s) include 3Dcontent organized as top and bottom fields in a frame. The 3D contentSEI messages may trigger the decoder 102 to analyze displaycapabilities. This analysis may be a result of a query directed todisplay 108, or a result of accessing pre-configured information inmemory concerning display capabilities. If non-3D display capabilitiesare detected, the decoder may elect to decode only one of the currentframe interlaced fields in response to the 3D option SEI message. Sinceonly one field is supplied by the decoder 102, the display 108 visuallypresents a two-dimensional (2D) image. Note, the decoder 102 may stillprovide both fields of a 3D view to a display 108, even if the displayis not enabled to present a 3D image.

In some aspects, the decoder 102 includes a 2D decision unit 110 tosupply 2D selection commands on line 112. The decoder 102 decodes onlyone of the current frame interlaced fields in response to the 2Dselection commands. In response, the display 108 visually presents a 2Dimage. The decoder 2D decision unit 110 supplies 2D selection commandsin response to a trigger such as receiving an SEI message on line 104.The trigger may be an analysis of display capabilities. For example,capabilities may be explored in communications with the display on line106. In other aspects, the trigger may be responsive to a manualselection made by the user and received on line 114. In another aspect,the trigger can be responsive to the receiver system configurationstored in memory 116.

The organization of top and bottom fields as complementary 3D views iscompatible with predictive encoding and decoding processes. With respectto MPEG standards, intra-coded frames (I-frames) are used to carryinformation that can be used as a foundation in a series of subsequentframes. With respect to H.264, the predictive frame is called anindependent decoder refresh (IDR) picture. In some aspects, the decoderaccepts a first encoded video frame prior to accepting the currentframe. The decoder 102 derives a predictive first frame top field and apredictive first frame bottom field from the first frame. Then, thedecoder 102 decodes the current frame top field in response to thepredictive first frame top field. Likewise, the current frame bottomfield is decoded in response to the predictive first frame bottom field.

Alternately, the decoder 102 derives a predictive first frame firstfield from the first frame. The first field may be either a top field ora bottom field. The decoder 102 decodes the current frame top field inresponse to the predictive first frame first field, and decodes thecurrent frame bottom field in response to the predictive first framefirst field.

FIG. 2 is a schematic block diagram of the present invention 3D videoencoding system. The system 200 comprises an encoder 202 having an inputon line 204 to accept a current 3D video image, including a first viewof the image and a second, 3D, view of the image. In some aspects, theencoder 202 accepts a stereo image. The encoder 202 encodes the firstview as a frame top field and encodes the second view as the framebottom field. The encoder 202 has a channel-connected output on line 104to supply a bitstream with a current video frame, having the top fieldinterlaced with the bottom field. The encoder 202 transmits thebitstream in a standard such as MPEG2, MPEG4, or H.264.

In one aspect of the system, the encoder 202 transmits a 2D commandresponsive to a trigger such as an analysis of connected receivercapabilities or the channel bandwidth. The analysis of receivercapabilities may occur as a result of accessing a memory 212 holding arecord of receiver capabilities. For example, record may show that aconnected receiver, or group of receivers, lacks 3D display capability.The analysis of channel bandwidth may be made as a result of accessingthe memory 212, or a result of receiving a real-time measurement ofbandwidth. In some circumstances the bandwidth may be small enough thatthe transmission of both fields is impractical. For these, andpotentially other reasons, the encoder 202 may elect to encode andtransmit only one of the fields from the current view frame.

In another aspect, the encoder 202 may transmit an SEI 3D optionalmessage, to signal 3D views available, to describe how 3D views aremapped into interlaced fields, and to describe dependency of each field.

In another aspect, the encoder 202 may transmit an SEI 3D option messagewith the current video frame, to trigger optional single fieldtwo-dimensional (2D) decoding. For example, if 2D receiver capabilitiesare discovered, the encoder 202 may transmit the SEI 3D option message,along with only one of fields.

Prior to accepting the current video image, the encoder 202 may accept afirst video image, and encode a first image top field, as well as afirst image bottom field. For example, the first image top and bottomfields may be used to form either an I-frame (MPEG) or an IDR picture(H.264). Then, the encoder 204 encodes the current frame top field inresponse to the first image top field, and encodes the current framebottom field in response to the first frame bottom field.

Alternately, a single field can be used to generate subsequent top andbottom fields. That is, the encoder 204, prior to accepting the currentimage, may accept a first video image and encode a first image firstfield. The first image first field may be either a top or bottom field.Then, the encoder 204 encodes the current frame top field in response tothe first image first field, and encodes the current frame bottom fieldin response to the first image first field.

Functional Description

FIG. 3 illustrates the present invention 3D view field interlacingprocess. Option 1 shows the left and right (stereo or 3D) views. Option2 shows the views as a composite video frame.

Instead of treating stereo-view video frames as separate frames or acomposite video frame, the present invention considers the sequence asinterlaced materials. For example, as illustrated in option 3, the leftview picture is the top field and the right view is the bottom field. Itis straightforward to code the interlaced video frames using existinginterlaced coding methods in different video coding standards, forexample, but not limited to, MPEG2, MPEG4, and H.264. The use of thesestandards enables better compression and bitstream handling.

Using the interlaced coding methods of the above-mentioned video codingstandards, a scalable decoding option can be supported with minimalrestrictions on the encoder side. The scalable option means that atleast one view (or field) can be decoded independently, withoutreferring to bitstream of the other view (or field). This option permitsdecoder and encoder devices to be used with legacy devices that do notsupport 3D display functionality. To enable this scalable coding option,all pictures are coded in field-picture mode. At least one field (eithertop or bottom) is self-contained; and for a self-contained field, thecorresponding field pictures can only use previously coded fieldpictures with the same parity as reference for motion compensation.

Here is a very brief summary of relevant H.264 coding tools. H.264 isthe latest international video coding standard. Relative to prior videocoding methods, some new inter-frame prediction options have beendesigned to enhance the prediction flexibility and accuracy. H.264permits multiple reference pictures to be used for inter prediction.That is, more than one prior coded picture can be used as references forinter prediction. To allow for better handling of interlaced materials,H.264 permits a video frame to be coded as either a frame picture, ortwo field pictures. The choice between these two options is referred toas picture-level adaptive-frame-field (PAFF) coding. This idea can beextended to the macroblock level, to enable the option ofMacroblock-level adaptive frame-field (MBAFF) coding.

FIG. 4 is a graph illustrating a comparison of coding performance.Experiments were conducted to evaluate the coding performance using theH.264 verification model JM7.3 software. The encoding parameters are: 5reference frames, +/− 32 pixel motion search range, 15-frame group ofpictures (GOP) with IPPP (an Intra-frame followed by 14 P pictures),RD-optimization (a JM software encoding option), CAVLC (context adaptivevariable length coding—an entropy option in the H.264 standard), and afixed quantization parameter (QP) of 28/32/36. A 300-frame stereosequence was coded in the following three settings:

-   -   1. Full frame coding (as option 2 in FIG. 3);    -   2. PAFF coding (as option 3 in FIG. 3, with no restriction on        reference pictures); and    -   3. Scalable field coding (as option 3 in FIG. 3, with        restriction on reference pictures).

The coding performances are shown in FIG. 4. The scalable field coding(setting #3) and PAFF coding (setting #3) essentially overlap. Bothsetting #2 and setting #3 have much better coding performance thansetting #1. The difference is roughly 0.8 dB at relatively high qualityside. The higher the peak signal-to-noise ratio (PSNR) values, thebetter the coding performance. So, for example, setting #2 is betterthan setting #1 (by 0.8 dB at the high bitrate side). Compared tosetting #2, setting #3 has very little overhead, less than 0.1 dB.

FIG. 5 is a flowchart illustrating the present invention method forreceiving 3D video. Although the method is depicted as a sequence ofnumbered steps for clarity, no order should be inferred from thenumbering unless explicitly stated. It should be understood that some ofthese steps may be skipped, performed in parallel, or performed withoutthe requirement of maintaining a strict order of sequence. The methodstarts at Step 500.

Step 502 accepts a bitstream with a current video frame encoded with twointerlaced fields. For example, the bitstream is a standard such asMPEG2, MPEG4, or H.264. Step 504 decodes a current frame top field. Step506 decodes a current frame bottom field. Step 508 presents the decodedtop and bottom fields as a 3D frame image. In some aspects, Step 508presents the decoded top and bottom fields as a stereo-view image. Inone aspect of the method, Step 503 accepts a 2D selection command. Forexample, the 2D selection command may be accepted in response to atrigger such as a supplemental enhancement information (SEI) message, ananalysis of display capabilities, manual selection, or receiver systemconfiguration. Then, only one of the current frame interlaced fields isused in response to the 2D selection commands. That is, either Step 504or Step 506 is preformed. As shown, Step 504 is performed (Step 506 isbypassed). Step 510 presents a 2D frame image. Alternately, both fieldsmay be decoded but a 2D frame image is presented in Step 510 in responseto using only one of the decoded current frame interlaced fields. In oneaspect of the method, simultaneous with the presentation of the 3D image(Step 508), Step 510 presents a 2D image in response to using one of thedecoded current frame interlaced fields. The simultaneous presentationof 2D and 3D images may represent that either the 2D or 3D view may beselected.

In another aspect of the method, Step 503 is organized into substeps,not shown. Step 503 a receives a (SEI) 3D content message with thecurrent video frame. Step 503 b analyzes display capabilities. If non-3Ddisplay capabilities are detected, only one of the current frameinterlaced fields is decoded. That is, either Step 504 or Step 506 isperformed. Then, Step 510 presents a 2D frame image.

In another aspect, Step 503 accepts an SEI 3D optional message, tosignal 3D views available, to describe how 3D views are mapped intointerlaced fields, and to describe the dependency of each field. Inanother aspect, Step 501 a accepts a first encoded video frame prior toaccepting the current frame. Step 501 b derives a predictive first frametop field. Step 501 c derives a predictive first frame bottom field.Then, decoding the current frame top field (Step 504) includes decodingthe current frame top field in response to the predictive first frametop field. Likewise, decoding a current frame bottom field (Step 506)includes decoding the current frame bottom field in response to thepredictive first frame bottom field.

Alternately, but not shown, Step 501 b derives a predictive first framefirst field, either a top field or a bottom field. In this aspect Step501 c is bypassed. Then, Step 504 decodes the current frame top field inresponse to the predictive first frame first field. Step 506 decodes thecurrent frame bottom field in response to the predictive first framefirst field.

FIG. 6 is a flowchart illustrating the present invention method forencoding 3D video. The method starts at Step 600. Step 602 accepts acurrent 3D video image, including a first view of the image and asecond, 3D, view of the image. In one aspect, Step 602 accepts a firstand second view of a stereo image. Step 604 encodes the first view as aframe top field. Step 606 encodes the second view as the frame bottomfield. Step 608 transmits a bitstream with a current video frame, havingthe top field interlaced with the bottom field, into a channel. Forexample, Step 608 transmits the bitstream in a standard such as MPEG2,MPEG4, or ITU-T H.264.

In one aspect, Step 607 accepts a 2D command responsive to a triggersuch as an analysis of receiver capabilities or the channel bandwidth.Then, Step 610 transmits the 2D command to a receiver. In one aspect,Step 610 transmits a supplemental enhancement information (SEI) 3Doption message with the current video frame to trigger optional singlefield two-dimensional (2D) decoding. In another aspect, Step 612transmits only one of the fields from the current view frame, if the 2Dcommand is transmitted in Step 610.

In one aspect, Step 601 a accepts a first video image prior to acceptingthe current video image. Step 601 b encodes a first image top field.Step 601 c encodes a first image bottom field. For example, an I-framemay be encoded for MPEG standard transmissions. Then, Step 604 encodesthe current frame top field in response to the first image top field,and Step 606 encodes the current frame bottom field in response to thefirst frame bottom field.

Alternately, Step 601 b encodes a first image first field, either a topfield or a bottom field, and Step 601 c is bypassed. Then, Step 604encodes the current frame top field in response to the first image firstfield, and Step 606 encodes the current frame bottom field in responseto the first image first field.

Systems and methods for 3D encoding and decoding have been provided.Examples have been given as to how the processes may be scaled for 2Dapplications. Examples have also been given for how the processes may beenabled with predictive coding. However, the present invention is notlimited to merely these examples. Other variations and embodiments ofthe invention will occur to those skilled in the art.

1. A method for receiving three-dimensional (3D) video in a receiversystem, the method comprising: in a receiver decoder: accepting anelectromagnetic waveform representing a bitstream with two interlacedfields, both encoded in a single first video frame, with a supplementalenhancement information (SEI) 3D content message; analyzing displaycapabilities in response to being triggered by the SEI 3D contentmessage; if 3D display abilities are detected, decoding a first frametop field from the first video frame and decoding a first frame bottomfield from the first video frame; if non-3D display capabilities aredetected, decoding only one of the first video frame interlaced fields;and, a display presenting an electromagnetic waveform representing thedecoded top and bottom fields as a 3D frame image if 3D capable, andpresenting a two-dimensional (2D) frame image if non-3D capable.
 2. Themethod of claim 1 wherein accepting a bitstream with first video frameencoded with two interlaced fields includes accepting the bitstream in astandard selected from the group including Motion Pictures ExpertGroup-2 (MPEG2), MPEG4, and ITU-T H.264 standards.
 3. The method ofclaim 1 wherein presenting the decoded top and bottom fields as a 3Dframe image includes presenting the decoded top and bottom fields as astereo-view image.
 4. The method of claim 1 further comprising: prior toaccepting the first video frame, accepting a first encoded video frame;deriving a predictive first frame top field; deriving a predictive firstframe bottom field; wherein decoding the first video frame top fieldincludes decoding the first video frame top field in response to thepredictive first frame top field; and, wherein decoding the first videoframe bottom field includes decoding the first video frame bottom fieldin response to the predictive first frame bottom field.
 5. The method ofclaim 1 further comprising: prior to accepting the first video frame,accepting a first encoded video frame; deriving a predictive first framefirst field; wherein decoding the first video frame top field includesdecoding the first video frame top field in response to the predictivefirst frame first field; and, wherein decoding the first video framebottom field includes decoding the first video frame bottom field inresponse to the predictive first frame first field.
 6. The method ofclaim 5 wherein deriving a predictive first frame first field includesderiving a predictive first frame top field.
 7. The method of claim 5wherein deriving a predictive first frame first field includes derivinga predictive first frame bottom field.
 8. The method of claim 1 furthercomprising: simultaneous with the presentation of the 3D image,presenting a 2D image in response to using one of the decoded firstframe interlaced fields.
 9. A method for encoding three-dimensional (3D)video in a transmitter system, the method comprising: in a transmitterencoder: accepting an electromagnetic waveform representing a 3D videoimage, including a first view of the image and a second view of theimage; encoding the first view as a top field in a single first videoframe; encoding the second view as a bottom field in the first videoframe; and, transmitting an electromagnetic waveform into a channelrepresenting a first video frame bitstream having the top fieldinterlaced with the bottom field in the single first video frame, and asupplemental enhancement information (SEI) 3D option message with thefirst video frame to trigger decoding selected from a group consistingof single field two-dimensional (2D) decoding, and top and bottom field3D decoding in a receiver decoder, depending on receiver capabilities.10. The method of claim 9 wherein transmitting the first video framebitstream having the top field interlaced with the bottom field includestransmitting the bitstream in a standard selected from the groupincluding Motion Pictures Expert Group-2 (MPEG2), MPEG4, and ITU-T H.264standards.
 11. The method of claim 9 wherein accepting a current 3Dvideo image, including a first view of the image and a second, 3D, viewof the image includes accepting a first and second view of a stereoimage.
 12. The method of claim 9 further comprising: accepting a 2Dcommand responsive to a trigger selected from the group including ananalysis of receiver capabilities and the channel bandwidth; and,transmitting the 2D command to a receiver.
 13. The method of claim 12further comprising: transmitting only one of the fields from the firstvideo view frame.
 14. The method of claim 9 further comprising: tuvisteprior to accepting the current video image, accepting a first videoimage; encoding a first image top field; encoding a first image bottomfield; wherein encoding the current frame top field includes encodingthe current frame top field in response to the first image top field;and, wherein encoding the current frame bottom field includes encodingthe first video frame bottom field in response to the first frame bottomfield.
 15. The method of claim 9 further comprising: prior to acceptingthe current image, accepting a first video image; encoding a first imagefirst field; wherein encoding the current frame top field includesencoding the current frame top field in response to the first imagefirst field; and, wherein encoding the current frame bottom fieldincludes encoding the current frame bottom field in response to thefirst image first field.
 16. The method of claim 15 wherein encoding afirst image first field includes encoding a first image top field. 17.The method of claim 15 wherein encoding a first image first fieldincludes encoding a first image bottom field.
 18. A three-dimensional(3D) video receiver system, the system comprising: a decoder having aninput connected to a channel to accept a bitstream with a single firstvideo frame encoded with two interlaced fields and an output to supply atop field and a bottom field, both decoded from the first video frame;and, a display having an input to accept the decoded fields, the displayvisually presenting the decoded top and bottom fields as a 3D frameimage; wherein the decoder receives a supplemental enhancementinformation (SEI) 3D content message with the first video frame,analyzes display capabilities, and, if non-3D display capabilities aredetected, decodes only one of the first frame interlaced fields inresponse to the 3D option SEI message; and, wherein the display visuallypresents a two-dimensional (2D) image.
 19. The system of claim 18wherein the decoder accepts the bitstream in a standard selected fromthe group including Motion Pictures Expert Group-2 (MPEG2), MPEG4, andITU-T H.264 standards.
 20. The system of claim 18 wherein the displayvisually presents the decoded top and bottom fields as a stereo-viewimage.
 21. The system of claim 18 wherein the decoder, prior toaccepting the current frame, accepts a first encoded video frame,derives a predictive first frame top field, derives a predictive firstframe bottom field, decodes the current frame top field in response tothe predictive first frame top field, and decodes the current framebottom field in response to the predictive first frame bottom field. 22.The system of claim 18 wherein the decoder, prior to accepting the firstvideo frame, accepts a first encoded video frame, derives a predictivefirst frame first field, decodes the first video frame top field inresponse to the predictive first frame first field, and decodes thefirst video frame bottom field in response to the predictive first framefirst field.
 23. The system of claim 22 wherein the decoder derives apredictive first frame top field.
 24. The system of claim 22 wherein thedecoder derives a predictive first frame bottom field.
 25. The system ofclaim 18 wherein the display, as a selected alternative to thepresentation of the 3D image, presents a 2D image in response to usingonly one of the decoded first video frame interlaced fields.
 26. Athree-dimensional (3D) video encoding system, the system comprising: anencoder having an input to accept a current 3D video image, including afirst view of the image and a second, 3D, view of the image, the encoderencoding the first view as a frame top field and the second view as theframe bottom field, interlaced in a single first video frame, and theencoder having a channel-connected output to supply a first video framebitstream; and, wherein the encoder transmits a supplemental enhancementinformation (SEI) 3D option message with the first video frame, totrigger decoding selected from a group consisting of single fieldtwo-dimensional (2D) decoding and top and bottom field 3D decoding inresponse to receiver capabilities.
 27. The system of claim 26 whereinthe encoder transmits the bitstream in a standard selected from thegroup including Motion Pictures Expert Group-2 (MPEG2), MPEG4, and ITU-TH.264 standards.
 28. The system of claim 26 wherein the encoder acceptsa first and second view of a stereo image.
 29. The system of claim 26wherein the encoder transmits a 2D command responsive to a triggerselected from the group including an analysis of connected receivercapabilities and the channel bandwidth.
 30. The system of claim 29wherein the encoder encodes and transmits only one of the fields fromthe first video frame.
 31. The system of claim 26 wherein the encoder,prior to accepting the current video image, accepts a first video image,encodes a first image top field, encodes a first image bottom field,encodes the current frame top field in response to the first image topfield, and encodes the first video frame bottom field in response to thefirst image bottom field.
 32. The system of claim 26 wherein theencoder, prior to accepting the current image, accepts a first videoimage, encodes a first image first field, encodes the first video frametop field in response to the first image first field, and encodes thefirst video frame bottom field in response to the first image firstfield.
 33. The system of claim 32 wherein the first image first field isa first image top field.
 34. The system of claim 32 wherein the firstimage first field is a first image bottom field.
 35. A three-dimensional(3D) video decoder, the decoder comprising: an input connected to achannel to accept a single first video frame bitstream encoded with twointerlaced fields and a supplemental enhancement information (SEI) 3Dcontent message with the first video frame; a two-dimensional (2D)decision unit to analyze the SEI 3D content message, and if non-3Ddisplay capabilities are detected in an associated display, decodingonly one of the first frame interlaced fields in response to the 3Doption SEI message; a 3D decision unit to analyze the SEI 3D contentmessage, and if 3D display capabilities are detected in the associateddisplay, decoding first frame interlaced top and bottom fields inresponse to the 3D option SEI message; and, an output to supply at leastone of the first video frame top field and the first video frame bottomfield.